1. Field of the Invention
The present invention relates to compound archery bows, such as bows and crossbows, in particular, to cams for the compound archery bows.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98.
Various designs of cams for compound archery bows are known in the art. Thus, U.S. Pat. No. 3,990,425 describes a bow with a cam comprising two limbs, each limb having a loose end, while the other ends of the limbs are connected with a handle. There are end members installed on the loose ends each of which includes a pulley for a bowstring and attachments for two cables. In the area of the loose end, each limb is divided into two portions with the pulley for the bowstring and the attachments located therebetween. Since the cables and the bowstring form a single continuous string such that the cables are crossed, friction appears between the cables when using the bow causing energy losses of an arrow and rapid wear-out of the cable.
U.S. Pat. No. 5,368,006 discloses a cam for an archery bow with cables and a bowstring being individual members. In the area of a loose end, each limb of the cam is divided into two portions with a pulley for the bowstring and attachments for the cables located therebetween. The cables are located on both sides of the bowstring and close to each other, since the pulley for the bowstring and the attachments, in fact, form a single member. Close positioning of the cables to the bowstring causes the cables to interfere with an arrow during a shot, thus requiring additional means to be used to retract the cables from the bowstring. Furthermore, like in the above case, the cables are crossed, resulting in friction energy losses and wear-out of the cable.
In a cam disclosed in U.S. Pat. No. 7,441,555, a bowstring is also located between two cables. However, in order to minimize the disadvantages of the cam of the U.S. Pat. No. 5,368,006, a portion of a limb is located between a pulley for the bowstring and each of attachments for the cables. This design suffers from an inconvenient way to set an arrow which is to be placed into the area confined by the cables going in parallel to the bowstring and on both sides thereof when the cam is in a free condition.
The closest prior art to the claimed invention is a cam for a compound archery bow according to patent application US20100206284. The application combines the advantages of the above bows and cams, namely, teaches cables to be located on the one side of a bowstring and being individual members. This is achieved by making such an end member which attachments for the cables are separated from a pulley for the bowstring and located on the one side of the pulley for the bowstring. However, this cam has a significant disadvantage that the cams according to U.S. Pat. No. 7,441,555 and U.S. Pat. No. 5,368,006 lack. Since in the US20100206284 the pulley for the bowstring is located not between the attachments for the cables but aside of them, and when pulling, a travel of the bowstring slightly exceeds a travel of the cables, lateral load appears acting on an axis supporting the pulley for the bowstring and the attachments for the cables. When the bowstring is strained, said axis tends to misalign thus causing increased wear of areas where end members are attached to loose ends and a stricter requirement to manufacturing quality of the axis, the pulley for the bowstring, the attachments for the cables and portions of limbs.